Add GitHub Actions for closing stale issues and pull request template

[ImBIOS]

Fixes #2698

Add a GitHub Actions workflow to close stale issues and a pull request template to ensure issues are closed when pull requests are merged.

• GitHub Actions Workflow for Closing Stale Issues

  • Create a new workflow file .github/workflows/stale.yml.
  • Use the actions/stale@v4 action to automatically close issues that have been inactive for 30 days.
  • Set days-before-stale to 30 and days-before-close to 7.
  • Exclude issues with the pinned or security labels from being marked as stale.

• Pull Request Template

  • Create a new pull request template file .github/PULL_REQUEST_TEMPLATE/pull_request_template.md.
  • Include verbiage like "This pull request closes #ISSUE_NUMBER" to ensure that an issue is closed when the pull request is merged.

• Documentation Updates

  • Update CONTRIBUTING.md to include sections about the new GitHub Actions workflow for closing stale issues and the new pull request template.

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[ImprovedTube]

hi and thank you!! @ImBIOS

• Contributors often use github's feature to close issue from the PR (example: Add z-index for button tooltip. #2707)
• Contributors often read latest issues first, but the number of comments and votes (thumbs) should also matter. (Github themselves moved to discussions including votes )
• All open issues might be equally relevant. Many relevant repos have chronically too few contributors, yet there is hopes and chance to finish many of them eventually.

@peterdanwan

• One could add a Github action to invite repeat-contributor to the organisation and the sub-group "contributors", which gives them triage rights to assign, close or label (If we cant find one such action, I think it is part of Github's API and AI can help us make that.) - Problem: If somebody bulk-removes / adds many labels, Github documents that, but there is no quick way to manage / undo that.